1. Field of the Invention
The present invention relates to an alkali-treated bagasse and its preparation and uses, more particularly to an alkali-treated bagasse whose structure is softened while preventing the decomposition of cellulose and hemicellulose, and a bagasse feed and a fermented bagasse feed prepared from said alkali-treated bagasse, as well as to their preparation and uses, and to a microorganism utilizable for fermenting said alkali-treated bagasse.
2. Description of the Prior Art
Although having been utilized in part as a fuel source, bagasse is a squeezed waste of sugar cane which contains a vast of cellulose and hemicellulose for which there have not yet been found other useful applications. The problem is that more than 100 million tons of bagasse produced annually worldwide have been still unutilized.
On the other hand, livestock fed with grass, or ruminants like cattle and sheep assimilate cellulose and hemicellulose of plants in nature, differerently from monogastric animals like human beings, pigs and poultry, and further physiologically utilize said cellulose and hemicellulose as an energy source.
Recently, the consumption of livestock products such as beef and dairy products has been increased so that an intensive livestock farming system has been remarkably developed to breed a lot of cattle standing in the same direction together in a small shed, and said intensive livestock farming system has tightened the supply of feed grass required for breeding and also has led the rapid increase of the demand for roughage containing cellulose and hemicellulose substitutable for feed grass.
There have been many studies to utilize bagasse as roughage for a long time, however, in addition of cellulose and hemicellulose, bagasse contains a considerable amount of lignin having a tight linkage with fibre like cellulose and said linkage tightens the structure of bagasse in the same manner as bamboo. While ruminants can assimilate bagasse itself, the digestibility of bagasse for ruminants is relatively low and the taste and nutrient value of bagasse for ruminants is very unpreferable. It is known that, when cattle assimilate a raw bagasse, there is a danger that pieces of said bagasse could be stuck into the walls of cattle's rumen.
For improving a nutrient value of bagasse, there were many proposals of increasing the digestibility of bagasse by decomposing lignin to soften the structure of bagasse. Most of said proposals comprise treating bagasse with an alkaline reagent and succeedingly fermenting the resultant alkali-treated bagasse. In such alkali treatment, as described in Biotechnology and Bioengineering, volume 26, pp. 426-433 (1984), it is known to use as an alkaline reagent sodium hydroxide and calcium hydroxide as well as sodium carbonate. In the fermentation of an alkali-treated bagasse, for instance, as described in Animal Feed Science and Technology, volume 9, pp. 1-17 (1983), an ensilage of an alkali-treated bagasse with sodium hydroxide is known.
We eagerly studied these conventional methods and found that in the case of an alkali treatment with sodium hydroxide, because of its strong alkalinity, a relatively small amount of sodium hydroxide was required to raise the pH of bagasse mixtures to a relatively-high level so that lignin was readily decomposed to soften the structure of bagasse without readily decomposing cellulose and hemicellulose necessary for roughage. In addition, it was found that the pH level of alkali-treated bagasse was decreased, specifically, said pH level was decreased very gradually over a long period of time to the range wherein lactic acid bacteria were proliferative, and further that a long period of 25 to 90 days was required for preparing a fermented bagasse feed from said alkali-treated bagasse. It was found that, in order to avoid said disadvantage and to increase rapidly the pH level of alkali-treated bagasse, said alkali-treated bagasse should be neutralized with an acid solution and there were many other drawbacks in conventional methods.
It was found that in the case of using calcium hydroxide and sodium carbonate, because of their relatively weak alkalinity, the amounts of alkaline reagents used was increased to the level of about 12 to 30 w/w % of the bagasse, d.s.b. (the wording of "w/w %" as referred to the invention will be abbreviated as "%" hereinafter), the cost of alkali treatment was raised and ruminants consuming excessively alkaline reagents desired a large amount of water so that they excreted a large amount of urine. Therefore it was found that the conventional alkali treatment has an extreme drawback by adversely physiologically affecting ruminants.